Previously, in a fuel supply device, which supplies fuel from an inside of a fuel tank of a vehicle to an outside of the fuel tank, a fuel pump, which is placed in the inside of the fuel tank, suctions the fuel into a suction inlet of the fuel pump and discharges the suctioned fuel to the outside of the fuel tank. The patent literature 1 discloses the above described type of fuel supply device. A suction filter is provided in this fuel supply device to suction the fuel into a suction inlet of the fuel pump after filtering the fuel through the suction filter in the fuel tank.
The suction filter, which is disclosed in the patent literature 1, includes a filter element that is placed in the inside of the fuel tank. Stored fuel, which is stored in the fuel tank, is passed into an inside space of the filter element through an outside surface of the filter element, so that the stored fuel is filtered through the filter element while a liquid film of the fuel is formed at the outside surface of the filter element. Here, the liquid film is maintained at the filter element as long as the outside surface of the filter element contacts the stored fuel. In the suction filter of the patent literature 1, an outside space of the filter element is partially covered with a storage member in the inside of the fuel tank. In this way, even in a case where the stored fuel is pulled to one side in the fuel tank to cause tilting of a surface of the stored fuel at the time of, for example, turning of the vehicle and thereby to cause separation of the surface of the stored fuel away from the filter element, a portion of the outside surface of the filter element can maintain contact with the fuel that is captured between the storage member and the filter element. Therefore, at the filter element that can be kept under the state, in which the formation of the liquid film is maintained, the fuel can be kept to be dominant as a suction subject to be suctioned into the inside space, in which the suction inlet opens.
However, in the suction filter of the patent literature 1, an inflow hole is formed at the storage member to supply the fuel at the space between the filter element and the storage member through the inflow hole. Therefore, at the time of, for example, turning the vehicle, the fuel, which is captured between the filter element and the storage member, can be easily leaked from the inflow hole in response to the tilting of the surface of the fuel. When the amount of the captured fuel, which is captured between the filter element and the storage member, is decreased, the captured fuel may possibly be depleted within a short period of time in response to progress of the suctioning of the fuel into the suction inlet. Thereby, the air may possibly be suctioned into the suction inlet. The suctioning of the air into the suction inlet causes a change in the discharge performance of the fuel pump and is thereby not desirable.
Furthermore, in the suction filter of the patent literature 1, the filter element is covered with the storage member, so that the surface area of the filter element becomes small. Thereby, when a pore size of pores of the filter element is reduced to improve the filtering function, a ratio of a clogged area, in which the pores of the filter element are clogged by foreign objects, tends to be increased at the surface of the filter element. Therefore, at the fuel pump, there is a possibility of deteriorating the stability of the discharge performance due to the clogging of the pores of the filter element.